Phototypesetting machine

ABSTRACT

The invention disclosed is a machine for projecting letters and other characters onto a strip of photographic material to form headlines and the like. The machine includes a disc having a number of concentric rings or fonts of characters which is spun at a constant high speed, a strobe light mounted on the opposite side of the disc from the paper and energized by a control circuit to project a desired character onto the paper, and a lens system for focusing the projected image. The disc and strobe assembly are slidable toward and away from the paper to vary the size of the image projected and, through a cam, move the lens to maintain proper focusing. A novel mounting arrangement maintains the optical center of the lens on the line from a reference point on the paper to a reference point on the letter to be projected so that a uniform horizontal reference line and uniform letter spacing are maintained regardless of the size of the letters projected. Vertical shifting of the font disc relative to the strobe light and the lens selects the particular font of characters to be projected. A paper drive system is incorporated to advance the paper a distance proportional to the size of the letter projected.

United States Patent [191 Hosterman [111 3,820,122 June 25, 1974PHOTOTYPESETTING MACHINE Harry L. Hosterman, Akron, Ohio [73] Assignee:Portage Newspaper Supply Company, Akron, Ohio 22 Filed: Aug. 16,1971

21 App]. No.: 171,941

[75] Inventor:

Primary Examiner-John M. Horan Attorney, Agent, or Firm-Oldham & OldhamCo.

[57] ABSTRACT The invention disclosed is a machine for projectingletters and other characters onto a strip of photo graphic material toform headlines and the like. The machine includes a disc having a numberof concentric rings or fonts of characters which is spun at a constanthigh speed, a strobe light mounted on the opposite side of the disc fromthe paper and energized by a control circuit to project a desiredcharacter onto the paper, and a lens system for focusing the projectedimage. The disc and strobe assembly are slidable toward and away fromthe paper to vary the size of the image projected and, through a cam,move the lens to maintain proper focusing. A novel mounting arrangementmaintains the optical center of the lens on the line from a referencepoint on the paper to a reference point on the letter to be projected sothat a uniform horizontal reference line and uniform letter spacing aremaintained regardless of the size of the letters projected. Verticalshifting of the font disc relative to the strobe light and the lensselects the particular font of characters to be projected. A paper drivesystem is incorporated to advance the paper a distance proportional tothe size of the letter projected.

19 Claims, 17 Drawing Figures ONE FOCAL LENGTH on l0 1 I ma LENGTH aPATENTED I974 3,820,122

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HARRY L. HOSTERMAN WM 9MM FIG. l6

ATTORNE YS PHOTOTYPESETIING MACHINE This invention relates to aphototypesetting machine for projecting a series of letters or otherindicia onto a strip of photographic material to form headlines or thelike and more particularly to a phototypesetting machine for projectinga letter or other indicia in the fonn of a negative image on a plasticsheet or disc onto a sheet of photographic paper.

The general system of phototypesetting by projecting individualcharacters onto a photographic sheet from a rapidly moving negativemaster by the action of a strobe light is well known in the art.However, prior phototypesetting machines have certain defects whichrender them difficult to use and which heretofore have been overcomeonly by complicated and expensive arrangements. Among these defects isthe difficulty in maintaining a sharp focus of the projected image onthe photographic paper strip when the size of the projected image isvaried. It is common practice to provide a turret lens arrangement sothat different lenses are used for different sized images. In such anarrangement, one lens is provided for each projected image size desired.The number of possible image sizes is thus limited and can be increasedonly by increasing the number of lenses provided and consequently, thecost and complexity of the phototypesetting machine.

In any phototypesetting equipment in which the projected image size canbe varied, provision must be made for varying the amount of photographicmaterial advanced after each image is projected so that uniform letterspacing can be maintained. While the prior phototypesetting machines doinclude paper feed mechanisms which accomplish uniform letter spacing,the control of the feed mechanism is not fully automatic but must beadjusted manually whenever the projected image size is changed. Also,the paper feed mechanism of the prior machines are not capable ofoperating accurately at high speeds and thus limit the speed at which aline of type can be generated to a level considerably below thecapability of the machine operator.

It is the primaryobject of the present invention to provide aphototypesetting machine in which a single lens system is employed andin which the lens is always maintained in a position relative to theimage bearing disc and the photographic paper so that a clear and sharpimage is focused on the paper, regardless of the size of the image beingprojected.

It is also an object of the present invention to provide aphototypesetting machine which all the images are projected onto auniform horizontal reference line and reference point, regardless of thesize of the image or the font from which the image is selected.

A further object of the invention is the provision of aphoto-typesetting machine in which the spacing of the letters on thephotographic material is proportional throughout the length of the lineof characters projected.

A still further object of the invention is the provision of aphototypesetting machine which is of simpler and more economicconstruction than the machines of the prior art.

Among other objects of the invention is the provision of aphototypesetting machine which has a photographic material advancingmechanism capable of maintaining proportional letter spacingautomatically 2 in accordance with the size of the image projected andwhich is capable of high speed operation.

Another object of the invention is the provision in a phototypesettingmachine of a photographic material advancing mechanism whichautomatically withdraws the paper or other photographic material from asupply magazine, advances the paper along a plane onto which letterimages are projected, and stores the exposed paper in a second magazine.

The above and other objects of the invention which will become apparentin the following detailed descriptionare achieved by providing aphototypesetting machine which employs a lens system mounted in slidingrelation to the font bearing disc and moved by a cam in response tomovement of the disc carrying subassembly so that the lens is maintainedat the proper focal point for any separation between the photographicpaper or other material and the font disc and, thus, for any size ofimage projected onto the paper. The lens system is vertically andhorizontally positioned by a rod which maintains the optical center ofthe lens on a line extending from a reference point in the plane of thephotographic paper to a reference point on the circle of the indiciabeing projected so that all indicia is projected onto a common line. Thefont disc is vertically shifted to change from one font of type toanother. The machine also includes a paper feed arrangement whichcompensates for any error in letter spacing due to the delay inmechanical movement of the feed control members to assure uniformspacing of the projected characters.

For a more complete understanding of the invention and the objects andadvantages thereof reference should be had to the followingspecification and the accompanying drawings wherein there is shown apreferred embodiment of the invention.

In the drawing: I

FIG. 1 is a side elevational view of the phototypesetting machine of thepresent invention, with portions of the assembly removed for clarity;

FIG. 2 is a vertical section taken along the line 2-2 of FIG. 1 andshowing the front elevation of the font assembly;

FIG. 3 is a vertical section taken along the line 3-3 of FIG. 1 andshowing the rear elevation of the font assembly;

FIG. 4 is a transverse sectional view taken along the line 4-4 of FIG.1;

FIG. 5 is a vertical sectional view taken along the line 5-5 of FIG. 1and showing the lens carriage assembly;

FIG. 6 is a fragmentary sectional view taken along the line 6-6 of FIG.3;

FIG. 7 is an elevational view of the font disc employed in the assemblyof the present invention;

FIG. 8 is a fragmentary vertical section taken along the line 8-8 ofFIG. 4;

FIG. 9 is a plan view of the paper feed subassembly;

FIG. 10 is a fragmentary sectional view taken along the line 10-10 ofFIG. 9 and showing the paper aligning rollers of the paper feedsub-assembly;

FIG. 11 is a fragmentary sectional view taken along the line 11-11 ofFIG. 9 and showing the take-up reel of the paper feed subassembly;

FIG. 12 is a schematic diagram of the control circuits of thephototypesetting machine;

ing a modified form of the invention in which the projected character isvisible to the machine operator;

FIG. is an isometric view of the assembled phototypesetting machine;

FIG. 16 is a fragmentary elevational view showing, in a schematicmanner, the mounting arrangement for the lens position control rod; and

FIG. 17 is a diagrammatic view illustrating the relative positions ofthe font disc, lens, and photosensitive paper for the projection ofvarious sizes of images.

As will be seen from FIG. I, the phototypesetting machine 10 consists ofa base 12 on which are supported an image projecting subassembly 14, alens subassembly 16, and a photographic paper feed subassembly 18. Theimage projecting subassembly 14 consists, basically, of a disc 20 whichcarries concentric rings of negative images of type characters andencoded identification data, a motor 22 for rotating the disc 20 at aconstant speed, a first lamp or lamps 24, a cylindrical lens 25 fordirecting the light from lamp 24in a narrow beam, and photodiode arraysor other sensing devices 26 and 28 for detecting the encoded data, and astrobe light 30 controlled by a firing circuit to project an image of anindividual character. The first lamp 24 illuminates the identifyingletter width data carried on the font disc 20 so that the data can besensed by the devices 26 and 28. Preferably, a red filter 64 covers thelamp 24 so thatthe light'from this lamp does not effect the photographicpaper. While specific reference is made to the use of photographicpaper, other photographic materials such as film may also be used. Theterm paper when used in this specification and claims is intended toencompass such materials.

The firing of the strobe light 30 occurs when the desired image isaligned with the light 30 and the lens assembly 16. The image is thusprojected onto a sheet of photosensitive paper 32 which is then advancedin proportion to the width of the projected image to move an unexposedportion of the paper 32 to receive the next image to be projected. Thesize of the image projected is varied by moving the font disc and strobesubassembly 14 toward or away from the plane of the paper 32. Obviously,the lens assembly 16 must also be moved to maintain sharp focusing ofthe image projected on the paper 32. As will be discussed in more detailbelow, the positioning of the lens assembly 16 is accomplished by a camarrangement which assures that the lens is in the proper relationship tothe disc 20 and to the paper 32 at all times. In order that the wordsgenerated on the paper 32 by the projection of successive images mayhave a common reference line, it is necessary that the projected imagesall meet a common reference point. As will be discussed in more detailbelow, this is achieved by a novel aligning arrangement which maintainsthe center of the lens of the assembly 16 on the optical center linepassing through a reference point fixed in the plane of the paper 32 anda reference point on the image carried on the disc 20.

FONT DISC SUBASSEMBLY The subassembly 14 is illustrated in FIGS. 14. Thesubassembly is supported by a carriage 34 which is supported on one ofits sides by a rod 36 connected to the base 12 by suitable brackets 38.Bushings 40 permit the carriage 34 to slide along the rod 36. Theopposite side of the carriage is supported by a roller 42 running on atrack 44 also mounted on the base 12. Extending upwardly from thecarriage 34 are two rods 46 and 48. A subframe 50 is slidably receivedon the rods 46 and 48 and this subframe carries the font wheel drivemotor 22 together with the font wheel 20. A disc 52 connected to themotor shaft 54 supports the font disc and a second disc 56 rotatablycarried on an arm 58 engages the opposite face of the font disc. A hingeconnection 60 connects the arm 58 to upwardly projecting portion 62 ofthe vertical subframe 50. The hinge joint 60 is an overcenter springloaded joint. The two information detecting devices 26 and 28 arecarried on the arm 58.

The subframe 50 is shifted vertically on the rods 46 and 48 by ashifting assembly consisting of the two shift wheel assemblies 66 and 68and the connecting link 95. This assembly is illustrated in FIGS. 2, 3,and 6. The upper shift wheel assembly 66 is carried by a plate 70connected to the subframe 50. The upper shift wheel 72 is journalled onthis plate 70. The wheel 72 has a pair of diametrically opposed notches74 and 74a which cooperate with a pawl 76 carried by the plate 70 topermit 180 rotation of the upper shift wheel 72. The lower shift wheelassembly 68 includes a plate 82 which is mounted to the carriage 34. Thelower shift wheel 84 is journalled on this plate in vertical alignmentwith the upper shift wheel 72. The lower shift wheel 94 is also providedwith a pair of diametrically opposed notches 86 and 86a and a pawl 88carried by the plate 82 permits 180 rotation of the lower shift wheel84. A link 95 is connected at one end to the lower shift wheel by a pin94 and atits opposite end to the upper shift-wheel by a pin 96. Thedistance between the pin 94 and the center of the lower shift disc 84 isone half the distance between the pin 96 and the center of the uppershift disc 72.

The upper shift wheel 72 and lower shift wheel 84 are connected topulleys 102 and 104, respectively, through magnetic clutches. Themagnetic clutch 114 of the lower shift wheel 84 is illustrated in FIG.6. As will be seen from FIG. 3,.the motor 22 is provided with a pulley98 which drives a belt 101 which is entrained over both of the shiftwheel pulleys 102 and 104. The belt 101 is also entrained over an idlerpulley 110 carried on the carriage 34 and vertically aligned with themotor pulley 98 and over additional idler pulleys 106 and 108 journalledon a bracket 112 which is carried on the carriage 34. The pulley 106 islocated so that the belt 101 travels a vertical path downwardly from thepulley 106 to the upper shift wheel pulley 102. This arrangementprovides a constant length belt path when the subframe 50 is shiftedvertically. When the subframe is moved vertically upwardly the length ofthe belt path between the pulley 106 and the upper shift wheel pulley102 decreases by an amount equal to the increase in path length betweenthe motor pulley 98 and the carriage mounted idler pulley 110.

The shift wheels may be controlled by the circuit shown in FIG. 13. Eachof the wheels 72 and 84 is provided with a small Alnico magnet 81 and93, respectively. A pair of reed switches 78 and and and 92,

, respectively, are mounted closely adjacent the wheels 72 and 84 atdiametrically opposite points on the circumference of the respectivewheel. The reed switches are positioned in relation to the magnet sothat one or the other of the reed switches is aligned with the magnetwhen the respective shift wheel is held fixed by its associated pawl 76or 88. FIG. 13 illustrates the clutch control circuit for the lowershift assembly. It will be understood that the upper shift wheelassembly is controlled by a similar circuit. The solenoid of the clutch114 is connected through a transistor 116 to a positive DC voltagesource. The collector of the transistor 116 is also connected to groundthrough the reed switches 90 and 92 connected in parallel and through atoggle switch 118 in series with the reed switches. When the toggleswitch 118 is in the position shown in FIG. 13, the circuit through thereed switches and the toggle switch is open. As a result, the transistor116 conducts and the solenoid 114 is energized. The clutch is engagedand the shift wheel 84 is now turned. As the magnet 93 approaches thereed switch 92 it will cause this switch to close completing a groundcircuit to the collector of the transistor 116 through the reed switch92 and the toggle switch 118. This groundcircuit will bias thetransistor 116 off, deenergizing the clutch 114. The pawl 88 now engagesthe notch 86 of the wheel 84 and holds the wheel in position until thetoggle switch position is reversed to again remove the ground circuitfrom the collector of the transistor 116.

The font disc is illustrated in FIG. 7. The disc 20 is circular and hasa central mounting hole 124. Alphabetic characters or other indicia 126are arranged in concentric circles 126a-l26d on the disc. Preferablyeach of the circles or rings 126a126d consists of one complete set ofcharacters of a single type style. In the embodiment shown, the outermost ring 126a consists of a complete set of capital italic letters; thering 126b, of capital Roman letters; and the inner rings 1260 and 126dof lower case italic and Roman letters. respectively. The characters ofthe rings are aligned so that each character in each ring is radiallyaligned with the same characters of the other rings. Each character 126is identified by a number expressed in binary code and this informationis carried in a ring 128 on the disc 20 with the binary number for eachcharacter being located 180 from its associated character. The disc 20also carries four rings 130a130d of marks which are associated with thecharacters located 180 from the respective marks and which indicate thewidth of the respective characters. A pulse mark 131 is also providedfor each character on the disc and these marks lead the width indicatingmarks 130a-d.

The vertical shifting of the subframe by means of 50 the shift wheelassemblies 66 and 68 in the manner described above shifts the disc 20vertically relative to the strobe light 30 and a line from the plane ofthe photographic paper 32 through the center of the lens of the assembly16 to bring one or the other of the circles of characters 126a-126d intoalignment with the light 30 and the projection line. A 180 rotation ofthe upper shift wheel 72 moves the font disc 20 a distance equal to twoof the rings of characters and thus effects a shift between the upperand lower cases of the same font style. A 180 rotation of the lowershift wheel 84 moves the font disc 20 a distance equal to one ring ofcharacters and thus effects a shift between the two font styles.

Movement of the carriage 34 and the font disc assembly 14 forwardly andrearwardly along the bar 36 and track 44 is accomplished by the linkagearrangement illustrated in FIG. 8. A crank wheel 132 is connected by acrank rod 134 to a bracket 136 attached to the font assembly carriage34. The wheel 132 is fixed to a shaft 138 which is journalled onsuitable brackets connected to the main frame 12. A bevel gear 140 isalso secured to the shaft and engages a mating bevel gear 142 which isaffixed to one end of a shaft 144 extending to a control knob 146. Sincethe link 134 is connected to the wheel 132 in an off center relation,rotation of the wheel 132 will move the carriage 34 forwardly orrearwardly. A rheostat or variable resistor 288 is also connected to theshaft 138 and, as will be described below, furnishes a control signalproportional to the size of the projected image.

LENS TRANSPORT ASSEMBLY The lens transport assembly is shown in FIGS. 1,4, and 5. The transport assembly 16 includes a transport carriage 148which is slidably supported on the rod 36 by a bushing 150 and on thetrack 44 by roller 152 carried at the end of an arm 154. Secured to anupwardly projecting portion 149 of the carriage 148 by a pivot pin 156is a vertical link 158. An upper horizontal link 160 is pivotallyconnected at one end to the upper end of the vertical link 158 and alower horizontal link 162 is pivotally connected at an intermediatepoint to the lower end of the vertical link 158 and the lens holdingassembly 164 is pivotally connected to the opposite end of the upperlink 160 and to one end of thelower link 162. The lens assembly 164mounts a lens 166. The lower arm 162 extends on the opposite side of thevertical link 158 and is provided at its second end with a ball joint168 which slidably receives a rod 170. The rod 170 projects rearwardlyand is slidably received in a ball joint 172 supported by the carriage34 of the font assembly 14. Preferably, the ball joint 172 is connectedto the carriage 34 by an adjustable mounting 173 which permits the balljoint to be shifted vertically between lower and upper positionsseparated by the height of a character on the disc. As will becomeapparent below, this arrangement permits either the upper or lower edgeof the letter to be selected as the reference point. One possibleadjustable mounting for this purpose is shown in FIG. 16. The ball joint172 is carried on an arm 175 which slides vertically in a bracket 187affixed to the carriage 34. An eccentric disc 177 contacts the arm 175to determine its height. Rotating with the eccentric 177 is a seconddisc 179 which is provided with diametrically opposed notches 181. Apawl 183 carried by the bracket 187 engages one of the notches 181 toprevisely locate the disc 179 and eccentric 177. A spring biases the arm175 downwardly to maintain the arm in firm contact with the eccentric177. It will be understood, of course, that other arrangements forachieving the vertical adjustability of the ball joint 172 may be usedin place of that described.

The rod 170 also projects forwardly through the ball joint 168 to a balljoint 184 which is carried in a bracket 176 affixed to the main frame12. The bracket 176 may be adjustable to permit the reference line to beshifted on the photosensitive paper. The centers of the ball joints 172and 174 are located in the planes of the font disc and the photographicpaper, respectively.

As will be seen from FIG. 5, the linkage arrangement 158-164 provides aparallelogram arrangement by which the lens 166 is moved exactlyopposite to the movement of the ball joint 168 at the end of the lowerlink arm 162. Thus, as the arm 162 moves to the right the lens moves tothe left, and, as the ball joint 168 moves upwardly the lens 166 movesdownwardly. It will be noted that the control rod 170 is angled relativeto the support rod 36 and that the angle of the rod 170 changes as thefont carriage 34 is moved toward or away from the plane of thephotographic paper 32. The arm 170 is so oriented that the opticalcenter of the lens 166 remains on a line passing from a reference pointon the plane of the photographic paper 32 to a reference point on thefont disc 20, regardless of the position of the font disc relative tothe plane of the photographic paper 32. I

Control of the position of the lens carriage 148 is achieved by a camarrangement illustrated most clearly in FIG. 4. A cam 178 which hasstraight cam surfaces 180 and 182 extending at right angles to oneanother, and a lug 184 extending from the intersection of the camsurfaces 180 and 182 at equal angles thereto is pivotally connected to adownwardly projecting leg 186 of the lens transport carriage 148. Thefirst cam surface 180 of the cam member 178 bears against a roller 188which is mounted on a bracket 190 secured to the main base 12. Thesecond cam surface 182 bears against a roller 192 which is carried by abracket 194 depending from the font assembly carriage 34. The rollers188 and 192 are arranged on a line parallel to the main support rod 36and track 44. The fixed roller 188 is fixed relative to the plane of thephotographic paper 32 while the roller 192 carried by the font assemblycarriage 34 is on a line extending parallel to the main support rod 36and passing through the center of the fix roller 188. The center of thefixed roller 188 is located one focal length of the lens 166 rearwardlyof the plane of the photographic paper and the center of the roller 192is located one focal length forwardly of the plane of the font disc. Theaxis .of the pivotal connection between the cam 178 and the downwardlyprojecting leg 186 is located at the intersection of a line parallel tothe cam surface 180 and passing through the center of the roller 188 anda line parallel to the cam surface 182 and passing through the center ofthe roller 192. This axis is one focal length from the line-joining thecenters of therollers 188 and 192.

It will be seen that as the font assembly carriage 34 is moved towardthe plane 32 of the photographic paper'the cam will be forced forwardlyand rotated so that the lens transport carriage 148 is also movedforwardly but at a rate varying with the position of the carriage 34relative to the plane of the photographic film 32 and the lens 166 isalways maintained in position so that the lens is in proper focus. Whenthe cam 178 is in its middle position, that is, when both of the camsurfaces 180 and 182 form 45 angles with the direction of movement ofthe font assembly carriage 34, there is an ambiguity of movement sincethe cam may turn in either direction upon further movement of thecarriage 34. The assembly shown in FIGS. 4 and 8 is provided to resolvethis ambiguity and assure that the cam 178 moves in the proper directionmoving the lens 166 also in the proper direction. The assembly consistsof an arm 196 projecting from the lens carriage 184 and mounting aroller 198 which is spring biased as indicated at 200 to engage a notch202 in a sliding member 204. The sliding member is received in suitablesupport blocks 206 and 208 connected to the main frame 12 with thesliding member 204 extending parallel to the main support rod 36.Pulleys 210 are provided at the opposite ends of the slide rod 204 andan endless belt 212 extends around the crank wheel 132 and the pulleys210 with the belt being anchored to the crank wheel at 214 and to thefont assembly carriage 34, as indicated at 216. It will be seen that theslide bar 204 will move forwardly or rearwardly depending on thedirection of rotation of the eccentric wheel 132. When the cam member178 is in its mid position the roller 198 will engage the bottom of thenotch 202 of the sliding member 204. The direction of movement of thesliding bar 204 is the same as the direction of move ment of thecircumference of drive wheel 132 so that during this interval the lenstransport carriage 148 is moved by the action of the slide bar 204acting on the roller 98. When the cam member 178 has passed through itscenter position the roller 198 moves up on the side of the notch 202.Thus, the notch 202 serves as a centering means to assure properpositioning of the lens when the cam is in its center position, as ameans for causing the cam member 178 to move in the proper directionwhen the cam'member 178 moves through its central or neutral position,and as a means to apply a spring force to keep the cam member 178against the roll 188 and 192.

The action of the cam 178 can be clearly seen in FIG. 17 where therelative positions of the font disc 20, lens 166 and photographic paper32 for projecting the largest, smallest, and unenlarged images areshown. These positions are indicated, respectively, in solid, dashed,and dash-dot lines. The relative positions of the points of contactbetween the rollers 188 and 192 and the camming surfaces 180 and 182,respectively, and the pivot point of the connection 184' are also shownfor the corresponding positions. FIG. 17 also illustrates the action ofthe lens positioning rod 172 which serves to maintain the projectedimages on a common reference line and with their leading edges at acommon reference point. In the arrangement shown, all the characters areprojected to a common reference point R, which corresponds to the lowerleft edge of the character. Since the photographic paper 32 faces towardthe lens and font disc, the projected characters when viewed as in FIG.17 are mirror images and the reference point R appears to be at thelower right comer. This, however is the leading edge of the letter. Inorder to achieve this uniformity, the center of the lens 166 remains onthe line from the reference point R, to the corresponding point R or thefont disc.

PAPER FEED ASSEMBLY The paper feed assembly is illustrated in FIGS.9-11. The assembly includes a support platform 218. A paper feedmagazine 220 supplies unexposed photographic paper which is entrainedover an idler roller 222, a first drive roller 224, through a guideplate assembly 226 to a second drive roller 230 and an encoder roller232 to a takeup magazine 236. The guide plate assembly 226 comprises afixed back plate 217 which is mounted in the support platform 218 and apair of front plates 219 and 221 which are spaced from the back plate217 to provide a slot 223 through which the photographic material ispassed. A window 228 is provided between the front plates 219 and 221 toexpose a short section of the photographic paper. The front plate 221 atthe exit end of the slot 223 is rigidly mounted on the support platform218 while the front plate 219 is pivotally connected to the supportplatform 218 by a pin 231. A rod 233 normally holds the plate 219 inparallel, closely spaced relation to the back plate 217. A spring 235carried by the plate 219 contacts the forward edge of the supportplatform 218 and biases the plate 219 away from the back plate 217 whenthe rod 233 is shifted away from the plate 217. As will be describedmore fully below, this arrangement permits automatic threading of a newstrip of photographic paper.

A paper brake is carried on the back plate 217 and includes a brakeplate 225 which is normally biased toward the front plate 219 to clampthe photographic paper against the front plate 219. A voice coil typeelectromagnetic 227 that is, an electromagnet which is capable ofpositive movement in both the forward and reverse directions, isconnected to the brake plate 225. In addition, a spring 239 may also beprovided to bias the brake plate toward the front plate 219. Theoperation of the paper brake will be described below.

The back plate 217 also carries a pair of aligning rollers 237, 237awhich engage the upper and lower edges, respectively, of thephotographic paper. As will be seen from FIG. 10, the rollers 237, 237aare guided by a vertical slot 241 in the back plate 217 and connected bya linkage arrangement 242 to a solenoid 243. The linkage arrangement 242is such that the rollers 237, 237a move equal amounts in oppositedirections. This assures that the horizontal centerline of thephotographic paper will remain at a fixed height above the supportplatform 218 regardless of the width of the paper.

The takeup magazine 236 is illustrated in FIGS. 9 and 11. The magazinehas a casing 253 which is provided with an opening 244 for receiving thepaper as it is passed from the drive roller 230 and the encoder roller236. The casing 253 may be formed of transparent red plastic so that thecontents of the magazine can be viewed while the exposed paper isprotected from light. A wind up spool 240 is provided in the center ofthe enclosure 253 and is attached to a magnetically attractable disc247. A permanent magnet disc 248 is located immediately below the disc247v and is attached by a pully 249 driven, through a belt, by a motor234. The supply magazine 236 is provided with a plurality of inwardlyprojecting spring fingers 238 whichldirect the incoming strip of papertoward the wind up spool 240. The surface of the spool 240 may beprovided with a rubber or other friction facing to grip the incomingpaper. The opening 244 of the enclosure 253 isprovided with a shutter245 to form a light-tight seal of the opening. A pin 246 mounted on thesupport base 218 engages the shutter when the magazine is properlypositioned to hold the shutter 245 open. A manually operated knife maybe provided adjacent the opening 244 of the magazine to cut the lengthof photographic paper. Preferably, means are provided in conjunctionwith the knife 25] to stop rotation of the wind up spool 240 when thepaper is cut to leave a short length of paper protruding from theopening 244 so that the paper may be withdrawn from the magazine forprocessing.

A suitable motor 234 drives the first drive roll 224, the second driveroll 230, and the winding spool 240 of the takeup magazine 236. Thefirst idler roll 222 is movable by means of a solenoid (not shown) to bebrought into and out of engagement with the first drive roll 224. Thissolenoid may also control the position of the rod (not shown) 233 whichholds the front plate 219 in parallel relation to the back plate 217.Likewise, the encoder roll 232 is controlled by a spring 232a.

The first idler roll 22 is brought into contact with the first driveroll 224 only during the initial threading of paper through the paperfeed mechanism. At this time the brake plate 225 is fully retracted bythe electromagnet 227, the rod 233 is shifted to its outer positionpermitting the front plate 219 to pivot away from the back plate 217into the position shown in dotted outline in FIG. 9, and the guiderollers 237 and 237a are moved to their uppermost and lowermostposition, respectively. The leading edge of the paper strip can now bethreaded manually from the supply magazine to the bite between the idlerroll 222 and the first drive roll 224. The paper is now pulled from thesupply magazine 220 and fed through the slot 223 to the second driveroll 230 and to the take up magazine 236. Since the plate 219 is shiftedaway from the back plate 217, the paper passes freely through the slot223. Suitable guide plates 224a and 230a may be provided to direct thepaper along the desired path. Upon completion of the threading sequence,the solenoid which moves the first idler roll 222 is deenergized to movethe idler roll 222 out of contact with the first drive roll 224 and tomove the rod 233 back to its normal position holding the front plate 219parallel to the back plate 217. At the same time the guide rollers 237and 237a are permitted to move toward one another so that'the paper isproperly centered horizontally. The electromagnet 227 is actuated at thesame time to clamp the paper in position.

During normal operation the first idler roll 222 is spaced slightly fromthe first drive roll 224 so that the first drive roll is normallyinoperative to move paper. The encoder roll 232 drives an encoder of thetype which generates a pulse for every fraction of a revolution of theencoder. The encoder roll 232 normally maintains pressure on the paperto hold the paper against the second drive roll 230. However, thispressure is insufficient to overcome the brake 225 so that no paper isadvanced unless the brake is released. The encoder thus operates onlyduring the advancement of paper and provides a pulse train proportionalto the amount of paper advanced. As the second drive roll 230 begins toadvance the paper, the paper will tend to wrap more tightly around thefirst drive roll 224 and as a result, the first drive roll 224 will pulladditional paper from the supply magazine 220. Preferably, the firstdrive roll 224 has a higher peripheral speed than does the second driveroll 230 so that the first drive roll 224 will feed additional paper ata rate sufficient to relieve tension on the paper between the two driverolls. This assures accurate advancement of the paper and uniform letterspacing.

CONTROL CIRCUITS FIG. 12 illustrates, schematically, the control circuitof the phototypesetting machine of the present invention. The keyboard250 is a standard binary coded electric keyboard which furnishes abinary coded signal for each character. When a character key of thekeyboard 250 is pressed an enabling signal is supplied to a counter 254.The counter receives pulses from the flash pulse diode 256 which is onediode of the photodiode array 26. The flash pulse diode 256 is actuatedby the pulse marks 131 on the font disc 20. Upon receipt of the enablingsignal from the keyboard 250 the counter counts three pulses from theflash pulse diode 256 and then resets the memory 252 by erasing thepreviously stored information. The counter 254 continues to count pulsesuntil five additional pulses are received, at which time the memoryadmits the identifying signal from the keyboard 250. The identifyingcode in the memory 252 is supplied to a match detector circuit 258 whichis continuously receiving the identifying code of each character on thefont disc from the letter code diodes 28. When a match occurs, that iswhen the identifying code from the keyboard 250 corresponds to the codesupplied by the letter code diodes 28 a signal is sent to the gate 260.The gate 260 is an NAND gate requiring a signal from the match detector258 and a pulse signal from the flash pulse diode 256. Upon receipt ofthe two signals the gate 260 energizes the single flash control circuit262 which, in turn, energizes the flash tube electronics 264 to fire thestrobe light 30. The selected character is thus projected to thephotographic film. The action of the counter 254 serves to assure thatthe leading edge of the pulse mark 131 always determines the time offiring of the strobe light 30. If, by coincidence, a particularcharacter key is depressed on the keyboard 250 at the same time theidentifying mark 128 of the same character on font disc is being scannedby thephotodiodes 26, a late triggering of the strobe light 30 wouldoccur in the absence of the counter 254. Since the counter 254 requiresa total of eight pulses to be recorded before the data code supplied bythe keyboard 250 is admitted to the memory 252, and since the'NAND gate260 cannot be energized until'the flash pulse from the diode 256 and thematch signal occur simultaneously, late firing is avoided. The maximumdelay is slightly less than one full revolution of the font disc 20 and,as the disc 20 rotates at a high speed, this delay is minimal. Thesingle flash control circuit 262 prevents the strobe 30 from being firedon the next and succeeding rotations of the disc.

In addition to energizing the flash tube electronics 264, the signalfrom the single flashcontrol circuit 262 is also supplied to a gate 266,which receives an input from an oscillator 268 and a control input fromthe length code diodes 26. The length code diodes 26 are responsive tothe length indicating marks l30a-130d of the front disc 20, theparticular mark being determined by the font and case of the characterbeing projected. The gate 266 operates to transmit pulses from theoscillator 268 to a register 270 for a length oftime determined by thelength code diodes 26. Thus, the signal supplied to the register 270 isa measure of the width of the projected letter. At the beginning oftransmission of pulses from the oscillator 268 to the register 270 asignal is sent to the brake electromagnet 272 to release the brake. Thesecond drive capstan 230 now begins to advance the paper and to drivethe encoder carried by the encoder roll 232. The encoder 272 furnishes aseries of pulses which is a measure of the amount of paper moved to theregister 270 and these pulses are subtracted from the pulses suppliedfrom the oscillator 268. When the register 270 has been brought back tozero count by the pulses from the encoder 272 the brake electromagnet227 is again energized, stopping the paper. Due to the slight mechanicaldelay in operation of the brake 225 a small additional amount of papermay be advanced. Thus, the encoder 272 will continue to supply pulses tothe register 270 and these pulses are stored as a negative count in theregister 270 to be subtracted from the next pulse sequence supplied fromthe oscillator 268. This arrangement assures uniform letter spacing asit, in effect, shifts the succeeding letter by an amount equal to theovertravel of the paper.

The space function 274, which is normally a part of the keyboard 250 butis shown as a separate function here for clarity, actuates a pulsegenerator 276 which supplies an actuating pulse to the gate 266 topermit the oscillator 268 to transmit a pulse train proportional to thewidth of space to the register 270. Thus, the space function 274 permitsthe paper to advance without the firing of the strobe light. The shiftand font functions 278 and 284, respectively, energize the correspondingcontrols and clutches to shift the disc assembly vertically, asdescribed above.

The size control rheostat 288 which, is described above, is controlledby the position of the font disc and lens, controls the oscillation rateof the oscillator 268 to vary the number of pulses supplied to theregister 270 in accordance with the size of the projected letter. Thus,when a large size letter is being projected, the oscillator 268 operatesmore rapidly to supply a larger pulse count to the register 270. Thesize control 288 also controls the paper drive motor 234, increasingmotor speed with increased projection letter size. The size controlrheostat 288 further serves, through the flash tube electronic circuit264, to control the intensity of the strobe light 30, the intensitybeing greater when large images are projected.

Additional control functions may also be provided. Thus, a kern control290 may be provided to decrease the spacing between adjacent letters toproduce a more uniform appearance of the line of type, for example,where an A is to follow a T. The kern control 290 is connected to theoscillator 268 to slow down the oscillator and, thereby, supply a lowerpulse count to the register 270. The repeat control 292 serves to resetthe single flash control circuit 262 so that the previously selected andidentified character which is stored in the memory 252 is againprojected. A recall function 294 can also be provided to project thelast letter selected without causing the printing of this letter. Therecall control function 294 actuates a solenoid 296 which moves a redshutter in front of the font disc so that only a red image is projectedtoward the paper, preventing the paper from being exposed. The recallfunction 294 also triggers the flash tube electronics 264 to projectlast selected character. It will be noted that the paper advancemechanism is not actuated by the recall function 294.

A viewing arrangement for permitting the operator to see the letterprojected, either when the letter is projected onto the photographicpaper or by operation of the recall function 294 is merely projected forviewing. A beam splitter 300 is carried in front of the font disc 20 onthe line from the strobe light through the lens 166 to the photographicmaterial 32. The beam splitter 300 is mounted on a suitable support 302carried by the font assembly sub-base 34 and serves to split the beamprojected through the disc into a first, primary beam which is directedto the photographic film 32 and to a second beam which is directeddownwardly to a prism 304 carried in a housing 306 which is alsosupported by the sub-base 34. The housing 306 carries a lens 308 whichhas infinity focus. The beam from the prism 304 through the lens 308passes through a second lens 310 carried by the paper feed subassembly18. The lens 310 restores the beam to a finite focus and directs it ontoa first mirror 312 which in turn projects the beam to a second mirror314 and hence to a viewing screen 318 positioned on or above keyboard250. Because the lens 308 is at infinity focus, the length of the pathbetween the lens 308 and 310 has no effect on the focus of the systemand no compensation is required for the variation in the distancebetween the front disc and the photographic paper. Each characterprojected to the photographic paper 32 is also projected along thesecond path and is visible to the operator on the viewing screen 308.When the recall function is operated the solenoid 296 moves a redshutter or filter 298 in front of the font disc 20 so that only a redbeam is projected. Since the photographic paper is insensitive to redlight the paper is not exposed but the projected character is visible onthe viewing screen 318.

It should now be apparent that the present invention providesaphototypesetting machine which is of less expensive and simplerconstruction than the machines of the prior art but which is of greaterversatility than the earlier machines. The cam arrangement for movingthe lens in coordination with the movement of the disc and strobe lightassembly towards and away from the photographic paper eliminates theneed for a multiple lens system while assuring accurate focusingthroughout the entire range of projected image sizes. By the novelarrangement of the control rod maintaining the optical center of thelens on the lines through the reference point on the plane of thephotographic paper and the reference point of the images on the fontdisc 20, the present invention assures that all characters will beprojected on a uniform base line regardless of the size of thecharacters. The paper feed arrangement is also an advance over those ofthe prior art since it automatically assures uniform spacing of theletters, regardless of the size of the projected image. The electronicsprovides a precisecontrol to the strobe and the movement of the paper.

It should be understood that while only the best known embodiment of theinvention has been illustrated and described in detail herein, theinvention is not so limited and the changes and additions may be made tothe invention without departing from the spirit thereof. Referenceshould thus be had to the appended claims in determining the true scopeof the invention.

What is claimed is:

l. A phototypesetting machine, comprising:

a base;

a supply of photographic paper supported by said base and includingmeans to hold a portion of the paper in a vertical plane;

a first carriage slidably mounted on said base for linear movementnormal to said vertical plane;

means to effect said linear movement of said carriage;

image projecting means mounted on said carriage to project the image ofa character toward said vertical plane;

a lens for focusing the projected image on said vertical plane; and

a lever assembly attached to said first carriage and to said lens toadjust the lens laterally and longitudinally relative to said planewhile maintaining the center of said lens on a straight optical axisthrough a reference point in said vertical plane and a correspondingreference point on the source of the projected image.

2. The phototypesetting machine according to claim 1 wherein said leverassembly comprises a rod attached to said first carriage by a connectionallowing pivotal and sliding movement of said rod, attached to said lensby a connection permitting pivotal and sliding movement of said rod, andpivotally supported at its forward end by a support maintaining thecenter of said rod in said vertical plane at a fixed distance from saidreference point of said plane.

3. The phototypesetting machine according to claim 1 further includingmeans responsive to the position of the carriage for maintaining thelens at the point necessary to focus the projected image on the verticalplane.

4. The phototypesetting machine according to claim 3 wherein thelastmentioned means includes a second carriage slidably mounted formovement between the vertical plane and the projecting means, and lensbeing carried by the second carriage, and a cam connected to the secondcarriage and having first and second surfaces engaging the firstcarriageand the base, respectively.

5. The phototypesetting machine according to claim 1 further includingmeans to advance the photographic paper to receive successive projectedimages.

6. The phototypesetting machine according to claim 5 wherein the meansto advance includes means to vary the amount of paper advanced inproportion to the size of the projected image.

7. The phototypesetting machine according to claim 6 which includes anoscillator, an arithmetic register, a gate for supplying a train ofpulses from the oscillator to the register, means for controlling thegate to vary the length of the pulse train in accordance with the widthof the projected image, pulse generating means responsive to papermovement for generating a second pulse train whose length is directlyproportional to the amount of paper advanced,- the second pulse beingsup plied to the register for subtraction from the pulse train stored inthe register, the means to advance the paper being responsive to thecontents of the register to advance paper only when the contents aregreater than zero.

8. The phototypesetting machine according to claim 7 further includingmeans for varying the frequency of the oscillator, said means beingresponse to the positions of the lens and font disc relative to thephotographic paper.

9. A phototypesetting machine, comprising:

a base;

a frame mounted on said base for holding a sheet of photographic paperin a vertical plane;

a carriage slidably mounted on said base for movement normal to thevertical plane;

a disc having at least one ring of negative images of characters, saiddisc being supported on the carriage in a plane parallel to the verticalplane of the photographic paper;

a motor for rotating said disc;

. a strobe light to project one of the characters of the disc onto thephotographic paper;

control means for the strobe light;

a lens between the disc and the paper for focusing the projected image;and

means to adjust the lens laterally and longitudinally relative to thephotographic paper while maintaining the optical center of the lens on astraight line extending from a reference point in the vertical plane toa corresponding reference point on the character on the disc.

10. The phototypesetting machine according to claim 9 further includinga second carriage supporting the lens and slidably mounted on the basefor movement normal to the vertical plane and cam means for maintainingthe lens at the point at which the projected image is focused on thevertical plane.

11. The phototypesetting machine according to claim 10 wherein the cammeans comprises a cam having two straight cam surfaces extending atright angles to one another, a first roller attached to the base withits axis of rotation in the vertical plane, the first roller contactingone cam surface, and'a second roller attached to the first carriage withthe axis of rotation of the second roller being parallel to that of thefirst roller and inter secting a line extending normal to the verticalplane and the axis of rotation of the first roller, the second rollercontacting the other cam surface, the cam being pivotally connected tothe second carriage by a pivotal connection located on the bisector'ofthe 90 angle between the cam surfaces.

12. The phototypesetting machine according to claim 10 wherein the meansfor maintaining the'optical center of the lines on the line between thetwo reference points comprises a parallelogram linkage connecting thelens to the second carriage and permitting movement of the lens relativeto the second carriage in a plane parallel to the vertical plane, and arod pivotally connected to the base at a point in the vertical plane,pivotally and slidably connected to the first carriage at a point fixedrelative to the reference point on the character on the disc, andpivotally and slidably connected to one link of the parallelogramlinkage.

13. The phototypesetting machine according to claim 9 wherein the dischas a plurality of concentric rings of images and wherein means areprovided for shifting the position of the.disc relative to the strobelight and the lens to any of a plurality of positions, one positionbeing provided for each ring of images.

14. The phototypesetting machine according to claim 13 wherein the discand the motor rotating the disc are carried by a subframe mounted forvertical movement on the carriage, the means for shifting the positionof the disc comprising means to move the subframe vertically.

15. The phototypesetting machine according to claim 14 wherein the lastmentioned means comprises a first wheel rotating about a firsthorizontal axis fixed relative to the carriage, a second wheel rotatingabout a second horizontal axis fixed relative to the subframe and inthesame vertical plane as the first horizontal axis, a link pivotallyconnected at one end to the first wheel in an off center relation and atits opposite end to the second wheel in an off center relation, andmeans for rotating the first and second wheels.

16. The phototypesetting machine according to claim 15 wherein thedistance between the pivotal connection at one end of the link and thecenter of the corresponding wheel is one half the distance between thepivotal connection at the other end of the link and the center of theother wheel.

17. The phototypesetting machine according to claim 15 wherein thewheels are mounted on shafts, each shaft having a pulley and a clutchconnecting the pulley to the shaft, the disc rotating motor having apulley, a first idler pulley being provided on the carriage in verticalalignment with the motor pulley, a second idler pulley being provided onthe carriage and aligned with the pulley of the upper one of the shaftsso that the second idler pulley and the upper one of the wheel drivingpulleys are tangent to a common vertical line, a belt being entrainedover the motor pulley, idler pulleys and wheel drive pulleys.

18. The phototypesetting machine according to claim 9 further includingmeans for moving the carriage comprising a disc mounted to the base forrotation'about an axis normal to the path of movement of the carriage,means to rotate the disc, and an arm pivotally connected at one end tothe disc in an off center relation and pivotally connected at itsopposite end to the carriage.

19. The phototypesetting machine according to claim 18 wherein the lensis supported by a second carriage movable along the same path as thefont disc support carriage, the means for maintaining the lens in focuscomprising a cam having two cam surfaces at right angles to one anotherand acted on respectively by a roller affixed to the base and a rolleraffixed to the font disc support carriage, the cam being pivotallyconnected to the second carriage, the means for moving the carriageincluding a bar slidably mounted on the base, a pulley at either end ofthe bar, an endless belt secured to the font support carriage and thecarriage moving disc and passing over the pulleys, the second carriagemounting a lens arm having a roller contacting the upper surface of thebar, the bar having a notch in its upper surface for engaging the rollerof the lever arm during a portion of the movement of the bar.

1. A phototypesetting machine, comprising: a base; a supply ofphotographic paper supported by said base and including means to hold aportion of the paper in a vertical plane; a first carriage slidablymounted on said base for linear movement normal to said vertical plane;means to effect said linear movement of said carriage; image projectingmeans mounted on said carriage to project the image of a charactertoward said vertical plane; a lens for focusing the projected image onsaid vertical plane; and a lever assembly attached to said firstcarriage and to said lens to adjust the lens laterally andlongitudinally relative to said plane while maintaining the center ofsaid lens on a straight optical axis through a reference point in saidvertical plane and a corresponding reference point on the source of theprojected image.
 2. The phototypesetting machine according to claim 1wherein said lever assembly comprises a rod attached to said firstcarriage by a connection allowing pivotal and sliding movement of saidrod, attached to said lens by a connection permitting pivotal andsliding movement of said rod, and pivotally supported at its forward endby a support maintaining the center of said rod in said vertical planeat a fixed distance from said reference point of said plane.
 3. Thephototypesetting machine according to claim 1 further including meansresponsive to the position of the carriage for maintaining the lens atthe point necessary to focus the projected image on the vertical plane.4. The phototypesetting machine according to claim 3 wherein the lastmentioned means includes a second carriage slidaBly mounted for movementbetween the vertical plane and the projecting means, and lens beingcarried by the second carriage, and a cam connected to the secondcarriage and having first and second surfaces engaging the firstcarriage and the base, respectively.
 5. The phototypesetting machineaccording to claim 1 further including means to advance the photographicpaper to receive successive projected images.
 6. The phototypesettingmachine according to claim 5 wherein the means to advance includes meansto vary the amount of paper advanced in proportion to the size of theprojected image.
 7. The phototypesetting machine according to claim 6which includes an oscillator, an arithmetic register, a gate forsupplying a train of pulses from the oscillator to the register, meansfor controlling the gate to vary the length of the pulse train inaccordance with the width of the projected image, pulse generating meansresponsive to paper movement for generating a second pulse train whoselength is directly proportional to the amount of paper advanced, thesecond pulse being supplied to the register for subtraction from thepulse train stored in the register, the means to advance the paper beingresponsive to the contents of the register to advance paper only whenthe contents are greater than zero.
 8. The phototypesetting machineaccording to claim 7 further including means for varying the frequencyof the oscillator, said means being response to the positions of thelens and font disc relative to the photographic paper.
 9. Aphototypesetting machine, comprising: a base; a frame mounted on saidbase for holding a sheet of photographic paper in a vertical plane; acarriage slidably mounted on said base for movement normal to thevertical plane; a disc having at least one ring of negative images ofcharacters, said disc being supported on the carriage in a planeparallel to the vertical plane of the photographic paper; a motor forrotating said disc; a strobe light to project one of the characters ofthe disc onto the photographic paper; control means for the strobelight; a lens between the disc and the paper for focusing the projectedimage; and means to adjust the lens laterally and longitudinallyrelative to the photographic paper while maintaining the optical centerof the lens on a straight line extending from a reference point in thevertical plane to a corresponding reference point on the character onthe disc.
 10. The phototypesetting machine according to claim 9 furtherincluding a second carriage supporting the lens and slidably mounted onthe base for movement normal to the vertical plane and cam means formaintaining the lens at the point at which the projected image isfocused on the vertical plane.
 11. The phototypesetting machineaccording to claim 10 wherein the cam means comprises a cam having twostraight cam surfaces extending at right angles to one another, a firstroller attached to the base with its axis of rotation in the verticalplane, the first roller contacting one cam surface, and a second rollerattached to the first carriage with the axis of rotation of the secondroller being parallel to that of the first roller and intersecting aline extending normal to the vertical plane and the axis of rotation ofthe first roller, the second roller contacting the other cam surface,the cam being pivotally connected to the second carriage by a pivotalconnection located on the bisector of the 90* angle between the camsurfaces.
 12. The phototypesetting machine according to claim 10 whereinthe means for maintaining the optical center of the lines on the linebetween the two reference points comprises a parallelogram linkageconnecting the lens to the second carriage and permitting movement ofthe lens relative to the second carriage in a plane parallel to thevertical plane, and a rod pivotally connected to the base at a point inthe vertical plane, pivotally and slidably cOnnected to the firstcarriage at a point fixed relative to the reference point on thecharacter on the disc, and pivotally and slidably connected to one linkof the parallelogram linkage.
 13. The phototypesetting machine accordingto claim 9 wherein the disc has a plurality of concentric rings ofimages and wherein means are provided for shifting the position of thedisc relative to the strobe light and the lens to any of a plurality ofpositions, one position being provided for each ring of images.
 14. Thephototypesetting machine according to claim 13 wherein the disc and themotor rotating the disc are carried by a subframe mounted for verticalmovement on the carriage, the means for shifting the position of thedisc comprising means to move the subframe vertically.
 15. Thephototypesetting machine according to claim 14 wherein the lastmentioned means comprises a first wheel rotating about a firsthorizontal axis fixed relative to the carriage, a second wheel rotatingabout a second horizontal axis fixed relative to the subframe and in thesame vertical plane as the first horizontal axis, a link pivotallyconnected at one end to the first wheel in an off center relation and atits opposite end to the second wheel in an off center relation, andmeans for rotating the first and second wheels.
 16. The phototypesettingmachine according to claim 15 wherein the distance between the pivotalconnection at one end of the link and the center of the correspondingwheel is one half the distance between the pivotal connection at theother end of the link and the center of the other wheel.
 17. Thephototypesetting machine according to claim 15 wherein the wheels aremounted on shafts, each shaft having a pulley and a clutch connectingthe pulley to the shaft, the disc rotating motor having a pulley, afirst idler pulley being provided on the carriage in vertical alignmentwith the motor pulley, a second idler pulley being provided on thecarriage and aligned with the pulley of the upper one of the shafts sothat the second idler pulley and the upper one of the wheel drivingpulleys are tangent to a common vertical line, a belt being entrainedover the motor pulley, idler pulleys and wheel drive pulleys.
 18. Thephototypesetting machine according to claim 9 further including meansfor moving the carriage comprising a disc mounted to the base forrotation about an axis normal to the path of movement of the carriage,means to rotate the disc, and an arm pivotally connected at one end tothe disc in an off center relation and pivotally connected at itsopposite end to the carriage.
 19. The phototypesetting machine accordingto claim 18 wherein the lens is supported by a second carriage movablealong the same path as the font disc support carriage, the means formaintaining the lens in focus comprising a cam having two cam surfacesat right angles to one another and acted on respectively by a rolleraffixed to the base and a roller affixed to the font disc supportcarriage, the cam being pivotally connected to the second carriage, themeans for moving the carriage including a bar slidably mounted on thebase, a pulley at either end of the bar, an endless belt secured to thefont support carriage and the carriage moving disc and passing over thepulleys, the second carriage mounting a lens arm having a rollercontacting the upper surface of the bar, the bar having a notch in itsupper surface for engaging the roller of the lever arm during a portionof the movement of the bar.